How to resize a bitmap eficiently and with out losing quality in android

Question

I have a Bitmap with a size of 320x480 and I need to stretch it on different device screens, I tried using this:

Rect dstRect = new Rect();
canvas.getClipBounds(dstRect);
canvas.drawBitmap(frameBuffer, null, dstRect, null);

it works, the image fills the whole screen like I wanted but the image is pixelated and it looks bad. Then I tried :

float scaleWidth = (float) newWidth / width;
float scaleHeight = (float) newHeight / height;
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap resizedBitmap = Bitmap.createBitmap(frameBuffer, 0, 0,
                width, height, matrix, true);
canvas.drawBitmap(resizedBitmap, 0, 0, null);

this time it looks perfect, nice and smooth, but this code has to be in my main game loop and creating Bitmaps every iteration makes it very slow. How can I resize my image so it doesn't get pixelated and gets done fast?

FOUND THE SOLUTION:

Paint paint = new Paint();
paint.setFilterBitmap();
canvas.drawBitmap(bitmap, matrix, paint);

If you found your own solution, you should add it as an answer to your question and accept it yourself so others do not add unwanted answers to your question. — Kuffs, Dec 01 '11 at 15:02

score 36 · Accepted Answer · edited Dec 01 '11 at 12:51

36

Resizing a Bitmap:

public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth)
{
    int width = bm.getWidth();
    int height = bm.getHeight();
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;
    // create a matrix for the manipulation
    Matrix matrix = new Matrix();
    // resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);
    // recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
    return resizedBitmap;
}

Pretty self explanatory: simply input the original Bitmap object and the desired dimensions of the Bitmap, and this method will return to you the newly resized Bitmap! May be, it is useful for you.

edited Dec 01 '11 at 12:51

eeerahul

1,629
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answered Dec 01 '11 at 12:16

Piyush

402
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@user924941 This one-time resize is better than resizing every frame. – Steve Blackwell Dec 02 '11 at 23:11
4

for a better quality scaled image Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, true); – Boris Karloff May 29 '13 at 20:24
@BorisKarloff: Setting the filter parameter has no effect when up-scaling, which the OP is interested in doing. – Ε Г И І И О Aug 12 '13 at 17:05
How do you call the function? – Si8 Feb 02 '14 at 20:33
7

Why not use Bitmap resizedBitmap = Bitmap.createScaledBitmap(originalBitmap, newWidth, newHeight, false); – slott Jun 03 '14 at 09:22
i want to only Resize width of image then how can it possible? – Vasant Apr 12 '16 at 07:27

score 0 · Answer 2 · answered Mar 14 '17 at 07:14

I am using the above solution to resize the bitmap. But it results portion of the image is lost.

Here is is my code.

 BitmapFactory.Options bmFactoryOptions = new BitmapFactory.Options();
            bmFactoryOptions.inPreferredConfig = Bitmap.Config.ARGB_8888;
            bmFactoryOptions.inMutable = true;
            bmFactoryOptions.inSampleSize = 2;
            Bitmap originalCameraBitmap = BitmapFactory.decodeByteArray(pData, 0, pData.length, bmFactoryOptions);
            rotatedBitmap = getResizedBitmap(originalCameraBitmap, cameraPreviewLayout.getHeight(), cameraPreviewLayout.getWidth() - preSizePriviewHight(), (int) rotationDegrees);

 public Bitmap getResizedBitmap(Bitmap bm, int newWidth, int newHeight, int angle) {
        int width = bm.getWidth();
        int height = bm.getHeight();
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;
        Matrix matrix = new Matrix();
        matrix.postRotate(angle);
        matrix.postScale(scaleWidth, scaleHeight);
        Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, true);
        DeliverItApplication.getInstance().setImageCaptured(true);
        return resizedBitmap;
    }

And here is the image height and width : Preview surface size:352:288 Before resized bitmap width : 320 Height : 240 CameraPreviewLayout width : 1080 Height : 1362 Resized bitmap width : 1022 Height : 1307

How to resize a bitmap eficiently and with out losing quality in android

2 Answers2

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